Population genetics and belonging

 

It is a time for a new book.This time I choosed one from a finnish scientist Venla Oikkonen "Population Genetics and belonging. This book opened my mind for a very intresting evolutionary topic, that I was never intrested in. After passing an exam on Evolution Biology, I hoped I will never need to have anything to do with this subject, but with a great book, as this one, everything has changed.


In the concept of race, humanity used the intricate way most of the time, and the races themselves were distinguished very arbitrarily. One of the many naturalists who tried to distinguish and describe our species was Johan Blumenbach¹ and his classification based largely on the description of human skulls, survived in our minds for the longest time. He distinguished 5 races of homo sapiens: White, red, yellow, black and brown. This was not the only division, because over the centuries our species tried to group many other theoreticians, take into account other factors, such as language, eye color, blood group, brain size.To illustrate how much these views differed from one another, one can look at the literature of the twentieth century, where two textbooks about all other opinions were published. One of them distinguished only in Europe 6 rases², while the other, in the same area, more than 30.
 

"(...)So many people still judged by their race
For such there never ought to be a place
'A fair go' those untruthful words I do recall
There is no such a thing as a 'fair go for all' (...)"
~ Francis Duggan

 The turning point in genetics was 1972. It was then that the geneticist Richard Lewontin, published the results of his study⁴, in which he examined 17 polymorphic sites, i.e. such regions in the genome that exhibit high variability (differences in the DNA sequence that appear in representatives of the same species ). Lewontin divided people into 8 groups, depending on their "race", and then studied their DNA. The results of his study turned out to be a surprise, because it turned out that the genetic variability of Homo Sapiens is much lower than the genetic variability observed in other species of mammals, including chimpanzees. The geneticist has proved that:
  1. Over 85% of the observed genetic variation in our species falls on intra-population variations, i.e. how members of one group differ from each other.
  2. Almost 8.5% of the observed genetic variability, assigned differences to local populations.
  3. And only 6.5% differences between the 8 groups of respondents.
In Botany and Zoology, it is assumed that to excite a species on the right, the difference between groups must be at least 25%, which, with our 6.5%, negates hypoethesia about the racial difference among homo sapiens.It is now assumed that between 83-90% of the total variability observed in humans is interpatellular variation, i.e. how much diwe people differ in themselves, not how the entire population of Asians differs from the entire population of Americans.In the article from 2016, the authors point out that a better allocation of people would be to study their origin than to classify them into artificial and sometimes problematic groups. There are people with black parents who have white skin and vice versa.



For the pigmentation in our bodies corresponds to several dozen genes, meanwhile, our entire genome counts over 20,000, so those responsible for our skin color or hair color are a very small fragment. In addition, skin color is an adaptation to the environment. People who live in areas where sun exposure during the day lasts a long time, and the intensity of sunraising is high, have darker skin than their distant neighbors from the Tropic of Cancer or Arctic Circle, where we are dealing with low levels of sunlight, and the intensity of the sun is not it's so high. It turns out that the pigment (melanin), which is found in human skin, as a result of melanocyte activity protects the deep layers of skin against excessive UV radiation emitted by the central star of our system. Melanin reflects the UV part, protecting us from the harmful and carcinogenic effects of ultraviolet radiation. Therefore, if the intensity of this radiation is high (such as in the equatorial climate zone), the skin color is darker due to the greater concentration of melanin in the skin.

In biological terms, body coloration is about many things, from adaptation to environmental conditions through passive forms of defense to reproductive success. We could equally divide people into mountain and lowland races, because populations that live high above the sea level tolerate low pressure better than those from low-lying areas. Thanks to this classification, a citizen of Berlin would be the same race as a citizen of Dhaka (Bangladesh).
There is agreement among scientists in this topic. Races are a sociological and cultural object, not an objective, biological fact. As a species, we are not sufficiently diversified to be able to distinguish any race among homo sapiens.

Evolutionary Nostalgia
We want to belong to a group, family, community, nation and we want to have a past⁶. That is why we want to differentiate ourselves from other group of people. That is why we can see prehistoric man like a Cheddar man or Kennewick man not through their similarities but through their differencies just to highlight pararell evolutionary trajectories.
Thanks to comercial genetic ancestry tests, people can be classified as a part of communities and differ from another.


Quelle:

¹ Blumenbach, J. F. De generis humani varietate nativa. 1. Auflage, Friedrich Andreas Rosenbusch, Göttingen 1775
² Boyd, William C., Genetics and the races of man; an introduction to modern physical anthropology, Little Brown and the Company, Boston, D.C Heath and Co. 1950
³ Carleton S. Coon, A study of the problems of race formation in man, Springfield 1950
⁴ Lewontin, R, The Appotionment of human diversity, Illinois 1972
⁵ Yudell M., Talking race out of human Genetics, Magazine Science, Mai 2016, Vol.51
⁶ Oikkonen V., Population Genetics and belonging,Palgrave Macmillan, Helsinki 2018

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